Weyl-Kondo Semimetal in non-Symmorphic Systems*

There is considerable current interest to explore electronic topology in strongly correlated metals. A promising setting arises in heavy fermion systems, which may feature not only strong correlations but also a large spin-orbit coupling. Recently, a Weyl-Kondo semimetal phase has been concurrently discovered in theoretical [1] and experimental [2] studies. The theoretical work was carried out in a Kondo lattice model that is time-reversal invariant but inversion-symmetry breaking. The defining characteristics of the Weyl-Kondo semimetal include linearly-dispersing Weyl nodal excitations with highly reduced velocity and the Weyl nodes being pinned to the Fermi energy. In this talk, I will summarize the theoretical developments, with a focus on the effect of non-symmorphic space-group symmetry in conjunction with strong correlations [1,3], the transitions to nearby quantum phases, as well as the efficient control of the Weyl nodes including their annihilation by a magnetic field [4,5]. The enrichment of these results for the global phase diagram of heavy fermion metals, reflecting on the role of spin-orbit coupling in the competion of quantum phases that develop out of the spin degrees of freedom [6], will be discussed.

[1] H.-H. Lai et al, PNAS 115, 93 (2018).
[2] S. Dzsaber et al, Phys. Rev. Lett. 118, 246601 (2017); ibid, arXiv:1811.02819.
[3] S. E. Grefe et al, Weyl-Kondo semimetal in non-symmorphic systems (2019).
[4] S. Dzsaber et al, arXiv:1906.01182.
[5] S. E. Grefe et al, Weyl-Kondo semimetal: towards control of Weyl nodes (2019).
[6] Q. Si and S. Paschen, Phys. Status Solidi B 250,425 (2013).